The present invention relates to the field of screen printing. Particularly, the present invention relates to an automatic method and apparatus for loading an article onto a printing surface of a printing machine.
Printed indicia for applying to items of clothing, such as T-shirts, sweatshirts, golf shirts, shorts, hats, and the like, as well as other cloth and paper goods, such as banners, posters, bags, flags, and the like, have become very popular over the last 20 years. Boutiques specializing in printing fanciful and textual indiciaxe2x80x94such as slogans, college names, sport team names and logos, licensed characters, and the likexe2x80x94these various media, are commonly seen in shopping malls across the country. The indicia available at these stores can be pre-printed on a substrate and applied with a heated press by operators at such boutiques to any of the aforementioned items purchased by a consumer or, more commonly, they can be screen printed directly onto the items in mass quantities for later retail sale.
In the screen printing process, a stencil screen is typically blocked (called xe2x80x9cmaskedxe2x80x9d in the industry) to embody the desired indicia and is then placed over the item to be printed. Ink of one color is then added to the screen surface and flooded onto the indicia by a flood bar of conventional design. The ink may be of any type well-known in the industry for screen printing. After the ink is flooded onto the screen, the ink is squeegeed through the screen interstices onto the item, leaving ink of the desired color where the interstices in the screen are unblocked. The squeegee can be of any type known in the art. The process may be repeated on each item as many as 16 times using different colors and complementing screens to create just the right design effect. Indexing the screens at each printing station makes this multiple color printing possible.
However, placement of these items onto the printing surface of a printing machine can be a critical factor in quality control. Placement of a screened image, on say a tee-shirt, may typically have only a one-eighth inch tolerance or less in any direction. The tolerance for placement on smaller items may be far less. For this reason, items must be placed with exacting precision onto the printing surface of the printing machine.
Adding to the problem, the printing machine operation may be on as fast as a three-second cyclexe2x80x94meaning an item is printed on every three seconds. In order to keep up with this pace the operator must be very quick to accurately index the printing item on the printing surface. Any mis-timings may cause loss of profit in the form of printing errors, operation shut-down, or, in a worst case scenario, injury to the operator.
Operators may use various indexing mechanisms, including their own hands and fingers, in order to be consistent in their placementxe2x80x94and consistency does not guarantee accuracy. However, the repetitiveness of the movement and tediousness of the work can dull the concentration of the operator, leading to printing mistakes. To safeguard against such mistakes occurring, the operator may be relieved by another operator after a period of time, introducing the probability of a modification to the item placement as no two operators will work exactly the same, or the operation may be shut down for periodic breaks for the operator, delaying operations and increasing costs.
Still, the continuously repetitive motion of the item placement can lead to carpal tunnel syndrome in some persons. Carpal tunnel syndrome is a condition created when the median nerve, traveling through the xe2x80x9ctunnelxe2x80x9d of the wrist bones, is compressed by the tendons also running through the carpal tunnel. The nerve responds to this compression by sending back pain signals, and by not carrying normal information to provide sensation and motor impulses to the hand.
Carpal tunnel syndrome is common, affecting 0.1% of the general population, and as many as 15% of workers in high-risk industries. The use of highly repetitive wrist movements appears to be correlated with the development of carpal tunnel syndrome, and the incidence rises with increasing repetition of hand use, and by a high level of force with each motion.
Therefore, it is advantageous to automate such a repeatable process. A few reasons for automatically loading an article onto a printing surface of a printing machine are: (1) to allow printing machine operators to concentrate on other areas of printing; (2) to diminish the likelihood of ruining printed articles; (3) to increase the repeatability of the exact placement of loaded articles; and, (4) to reduce the injury risk to printing machine operators.
In accordance with the present invention, new methods and apparatus for automatically loading a textile onto a printing machine are provided. The apparatus includes a first support structure having a surface including a first area and a second area, and adapted to support at least one textile thereon. A second support structure is also provided proximate the second area of the first support structure, having a textile lifting mechanism and a textile transfer mechanism.
It is therefore an aspect of the present invention to provide an automatic textile loader wherein the first support structure is a conveyor table having a primary textile indexing mechanism, such as a laser created line, a vertical stop, or a compact table with angled side edges. The indexing mechanism may be contoured to approximate a periphery of a portion of the textile. Supplemental or secondary indexing mechanisms may also be used, including lasers or the like.
It is a further aspect of the present invention to provide an automatic textile loader wherein the preferably adjustable conveyor table includes a plurality of continuous moving belts for transporting the textile from the first area to the second area of the support structure surface. The number of belts used may vary widely with the width and length of the conveyor table. The table may include an interrupt device, such as an infrared sensor or mechanical switch, for stopping the movement of the continuous belts.
It is another aspect of the present invention to provide an automatic textile loader wherein the textile lifting mechanism includes at least one adjustable pick-and-place mechanism, preferably either pneumatic, hydraulic, mechanical, or electronic, arranged individually, in pairs, or groups of three or more. Similarly, the textile transfer mechanism includes at least one adjustable pick-and-place mechanism, which may be either pneumatic, hydraulic, mechanical, or electronic, arranged individually, in pairs, or groups of three or more. Preferably, the second support structure is a metal frame and the textile lifting mechanism and the textile transfer mechanism are mounted to the frame.
Another aspect of the present invention is to provide an automatic textile loader having a limit sensor on each of the lifting pick-and-place mechanisms adapted to detect the top of the textile. Also, as part of the lifting pick-and-place mechanisms, a first actuatable extension provides a link for each pick-and-place mechanism to the support structure and a travel path for the pick-and-place mechanism in one direction. A second actuatable extension provides a link for each pick-and-place mechanism to the support structure and a travel path for the pick-and-place mechanism in a second direction. And, a third actuatable extension providing a link for each pick-and-place mechanism to the support structure and a travel path for the pick-and-place mechanism in a third direction.
It is still another aspect of the present invention to provide an automatic textile loader wherein the second support structure includes a track for guiding horizontal movement of the transfer mechanism. The transfer mechanism comprising an adjustable extension for providing a link for each pick-and-place mechanism to the track and a travel path for the pick-and-place mechanism in a first direction. An actuatable extension provides a link for each transfer pick-and-place mechanism to the adjustable extension and a travel path for the pick-and-place mechanism in a second direction.
In a method for automatically loading a textile onto a printing machine, it is an aspect of the present invention to convey a textile along a support surface from a first area on the surface to a second area on the surface, then lift the textile from the second area to an elevated position, then transfer the textile from the elevated position to a printing machine.
It is an aspect of the present method to provide a reproducible placement of the textile on the printing machine. It is therefore as aspect to index the textile at the first area of the surface. In the method for automatically loading a textile, it is an aspect of the present invention to index the textile by providing a mark at the first area of the support surface, and then lining the textile up on the support surface with the mark.
These and other aspects of the present invention set forth in the appended claims may be realized in accordance with the following disclosure with particular reference to the accompanying drawings.